WEBVTT - TechStuff Classic: How Solar Towers Work 0:00:04.400 --> 0:00:12.239 Welcome to tech Stuff, a production from iHeartRadio. Hey there, 0:00:12.280 --> 0:00:15.560 and welcome to tech Stuff. I'm your host, John Vin Strickland. 0:00:15.640 --> 0:00:19.000 I'm an executive producer with iHeartRadio and how the tech 0:00:19.120 --> 0:00:22.799 are you. It is time for a classic episode of 0:00:22.840 --> 0:00:25.680 tech stuff, and that means we're gonna be taking a 0:00:25.680 --> 0:00:30.360 look at how solar towers work. This episode originally published 0:00:30.360 --> 0:00:34.840 on March ninth, twenty sixteen. It's an interesting way of 0:00:35.000 --> 0:00:38.640 harnessing energy from the Sun that does not involve directly 0:00:38.760 --> 0:00:43.920 transmitting or translating photons to electricity the way a solar 0:00:43.920 --> 0:00:47.760 panel would. So sit back and enjoy this classic episode 0:00:47.800 --> 0:00:50.600 of tech stuff. Today, I want to talk a little 0:00:50.600 --> 0:00:53.559 bit about solar towers, which is a different way of 0:00:53.600 --> 0:00:56.840 harnessing the Sun's energy, and I think it's a really 0:00:56.880 --> 0:01:01.600 clever way as well, because it doesn't rely on sunlight 0:01:01.720 --> 0:01:06.720 hitting a panel. Obviously, the big big drawback to that 0:01:06.800 --> 0:01:10.400 approach is when the sun isn't hitting a panel, you're 0:01:10.440 --> 0:01:14.280 not generating any electricity. Right, So if it's super cloudy 0:01:14.760 --> 0:01:17.640 or if it's nighttime, if the sun is not able 0:01:17.680 --> 0:01:20.640 to hit the panel, the sunlight's not getting there, you 0:01:20.720 --> 0:01:23.960 have nothing to convert into electricity and your solar panels 0:01:24.040 --> 0:01:28.120 go on to be unused for that duration. So that 0:01:28.160 --> 0:01:30.720 can be really rough if you have a long stretch 0:01:30.800 --> 0:01:33.800 of overcast days, or you live in a place where 0:01:34.640 --> 0:01:38.560 you don't get solar exposure at your house because of 0:01:38.760 --> 0:01:42.160 maybe they're taller buildings around you, or trees or whatever 0:01:42.200 --> 0:01:44.240 it may be. Maybe you have a north facing house 0:01:45.160 --> 0:01:47.760 rather than a south facing house here in the Northern Hemisphere. 0:01:48.320 --> 0:01:50.560 If you have a south facing house in the Northern Hemisphere, 0:01:50.560 --> 0:01:52.680 you're going to get more solar exposure than a north 0:01:52.720 --> 0:01:57.040 facing house, So solar panels have that drawback. They're also 0:01:57.200 --> 0:02:01.240 there's efficiency issues with solar panels. When we talk about efficiency, 0:02:02.240 --> 0:02:05.240 what we mean is how much of the sun's energy 0:02:05.280 --> 0:02:08.760 can we actually convert into electricity and how much of 0:02:08.800 --> 0:02:11.040 it do we lose? How much of that energy bounces 0:02:11.080 --> 0:02:14.320 off the panel and we do not capture it. Most 0:02:14.639 --> 0:02:17.160 commercial solar panels, the kind that you would put on 0:02:17.240 --> 0:02:20.560 your house, the efficiency is around eleven to fifteen percent, 0:02:21.200 --> 0:02:25.520 meaning that you're losing a lot, like eighty five percent 0:02:25.600 --> 0:02:30.520 of that energy is not converting into electricity. What that 0:02:30.560 --> 0:02:33.720 means is that you have to buy more solar panels 0:02:34.120 --> 0:02:37.880 to cover more space to collect more solar energy to 0:02:37.960 --> 0:02:41.640 generate enough electricity to meet your needs. Obviously, if solar 0:02:41.639 --> 0:02:44.360 panels were one hundred percent efficient, which is impossible by 0:02:44.360 --> 0:02:47.800 the way, physically impossible. People have proved it with masth, 0:02:48.720 --> 0:02:52.600 then if it were one hundred percent efficient, you wouldn't 0:02:52.600 --> 0:02:55.400 need as many solar panels in order to do what 0:02:55.520 --> 0:03:00.400 you need to do. That's just not the case in reality. Instead, 0:03:01.040 --> 0:03:03.400 we often have to buy more than what we would 0:03:03.680 --> 0:03:07.640 like cover a larger area. And even then again you're 0:03:08.200 --> 0:03:11.720 limited to collecting electricity or generating electricity i should say, 0:03:12.400 --> 0:03:15.320 during the daylight hours. An electricity also is a use 0:03:15.360 --> 0:03:18.040 it or lose it kind of thing, meaning that if 0:03:18.080 --> 0:03:20.960 you don't have an immediate use for that electricity and 0:03:21.000 --> 0:03:23.160 you don't have a way to store it, you lose 0:03:23.200 --> 0:03:25.679 that electricity. You have to use it when it's generated, 0:03:26.720 --> 0:03:29.040 so you need to have some sort of battery system 0:03:29.040 --> 0:03:31.760 as well, so that in the times when you're not 0:03:32.240 --> 0:03:34.720 using the electricity you're generating, you can still save it 0:03:34.800 --> 0:03:38.320 for later use. And until recently, batteries have been really 0:03:38.360 --> 0:03:41.360 expensive for the home, but Tesla's powerwall has kind of 0:03:41.440 --> 0:03:44.680 led a revolution in that space and we're starting to 0:03:44.720 --> 0:03:49.240 see more affordable versions of batteries hit the home market. Okay, 0:03:49.280 --> 0:03:51.360 all that's out of the way to just say that 0:03:51.400 --> 0:03:56.280 the traditional solar panel approach has its drawbacks. Now, let's 0:03:56.280 --> 0:03:59.600 talk about solar towers, because they take a totally different 0:03:59.640 --> 0:04:04.240 approach to harnessing electricity from the sun, and it's really 0:04:04.280 --> 0:04:07.640 pretty clever. And they can harness electricity or they can 0:04:07.680 --> 0:04:10.960 generate electricity day or night. So you might wonder, well, 0:04:10.960 --> 0:04:13.520 how is that possible? And when the Earth rotates so 0:04:13.600 --> 0:04:16.400 that the sun is no longer shining on a solar tower, 0:04:17.080 --> 0:04:20.920 where's that electricity coming from. So here's the way it works. Now, 0:04:20.920 --> 0:04:25.800 I'm largely going to refer to a company called Solar Reserve, 0:04:25.880 --> 0:04:29.120 which is here in the United States. Solar Reserve is 0:04:29.160 --> 0:04:33.719 just one company that is building structures like these around 0:04:33.720 --> 0:04:36.560 the world, So I don't mean to suggest they're the 0:04:36.640 --> 0:04:39.240 only one. I'm using them as the example because that 0:04:39.320 --> 0:04:43.160 so much of their information is available to actually read 0:04:43.200 --> 0:04:49.080 about and understand. So it's a really helpful approach. Solar towers. Well, 0:04:49.080 --> 0:04:52.160 first of all, the name kind of gives away the 0:04:52.200 --> 0:04:55.160 main feature. There's a tower at the center of this 0:04:56.120 --> 0:04:59.800 structure or really multiple structures. So how tall are these 0:05:00.000 --> 0:05:02.039 hours Well, according to Solar Reserve, the height of the 0:05:02.120 --> 0:05:05.080 tower and its thermal receiver. More on that in just 0:05:05.120 --> 0:05:08.800 a second tends to be six hundred forty feet combined, 0:05:08.960 --> 0:05:12.160 or about one hundred and ninety five meters. So you've 0:05:12.200 --> 0:05:17.039 got this tower in a large area. You want to 0:05:17.080 --> 0:05:19.880 have an area that gets a lot of solar exposure, 0:05:19.960 --> 0:05:23.600 otherwise this is not a practical way of generating electricity. 0:05:23.640 --> 0:05:27.240 So imagine like a desert, nice flat desert, lots of 0:05:27.360 --> 0:05:31.240 sunlight hitting that dessert every typical day, and you have 0:05:31.360 --> 0:05:33.960 a tall tower with a receiver on the top of it. 0:05:34.040 --> 0:05:39.160 Now that receiver is actually a series of dark panels. 0:05:39.520 --> 0:05:42.080 And these aren't solar panels, not in the way that 0:05:42.160 --> 0:05:44.200 you would put on top of your house. They are 0:05:44.240 --> 0:05:49.440 not converting sunlight into electricity directly. Rather, they are panels 0:05:49.480 --> 0:05:54.440 that transfer thermal energy. In other words, they're all about 0:05:54.520 --> 0:06:00.479 transmitting heat. So these panels have sixty six thin wall 0:06:00.680 --> 0:06:04.320 straight tubes in them. Those tubes are designed to conduct 0:06:04.400 --> 0:06:07.000 heat from the outside to the inside of that tower, 0:06:07.839 --> 0:06:10.480 and the tubes are made out of a steel alloy 0:06:10.600 --> 0:06:14.600 that's covered in a high absorptivity black coating to maximize 0:06:14.640 --> 0:06:18.039 the amount of energy the panel can absorb. So you've 0:06:18.080 --> 0:06:21.040 got sunlight shining on this tower, Well, how is that 0:06:21.160 --> 0:06:24.800 enough to generate electricity on its own. It's not. In fact, 0:06:24.839 --> 0:06:28.400 what you end up doing is surrounding the tower with mirrors. Now, 0:06:28.440 --> 0:06:32.800 Solar Reserve uses mirrors that they call heliostats. These heliostats 0:06:32.839 --> 0:06:38.560 are mounted on arms essentially that allow them to track 0:06:38.720 --> 0:06:42.680 the motion of the sun. That way, the mirrors maintain 0:06:42.800 --> 0:06:47.920 the ideal angle to reflect the sun's light directly toward 0:06:48.120 --> 0:06:51.359 the top of that tower at that receiving point of 0:06:51.400 --> 0:06:55.320 the tower on those panels. And we're talking about a 0:06:55.400 --> 0:07:00.440 lot of mirrors. Solar Reserve has one area called the 0:07:00.480 --> 0:07:04.920 Crescent Dunes. That's their tower that they have in the US, 0:07:05.680 --> 0:07:08.599 and the Crescent Dunes towers surrounded by more than ten 0:07:08.760 --> 0:07:13.360 thousand mirrors, covering a fifteen hundred acre field. So this 0:07:13.440 --> 0:07:16.040 is a big operation. You've got to have a lot 0:07:16.080 --> 0:07:19.520 of open land for this to work. That's obviously one 0:07:19.560 --> 0:07:23.559 of the potential drawbacks, right that you need a place 0:07:23.560 --> 0:07:25.920 that's going to have a lot of solar exposure, and 0:07:26.000 --> 0:07:28.800 you need to have enough space to make it make sense. 0:07:29.240 --> 0:07:31.080 But assuming you have both of those things, you can 0:07:31.080 --> 0:07:34.920 do something pretty incredible. We'll be back with more about 0:07:34.960 --> 0:07:48.040 how solar towers work after these messages. So what these 0:07:48.280 --> 0:07:51.160 mirrors do is direct that sunlight up at those dark 0:07:51.160 --> 0:07:54.040 panels I was talking about. Remember I mentioned there were fourteen. 0:07:54.400 --> 0:07:57.440 These fourteen panels are divided up into two groups of seven. 0:07:58.320 --> 0:08:01.800 Each group of seven represent kind of a circuit, and 0:08:01.880 --> 0:08:05.200 that circuit is not for electricity. It's rather for a 0:08:05.240 --> 0:08:11.440 circuit of pipes that are circulating liquid salts. So liquid 0:08:11.440 --> 0:08:14.920 salts are pretty cool, which is a weird way of 0:08:14.920 --> 0:08:17.920 putting it when you're talking about thermal energy, But liquid 0:08:17.920 --> 0:08:22.480 salts can hold on to more heat than water can 0:08:23.200 --> 0:08:26.880 and can remain in liquid form, so in other words, 0:08:26.880 --> 0:08:31.000 they don't vaporize into steam. And what solar reserve does 0:08:31.280 --> 0:08:35.920 is it pumps around five eight hundred gallons of liquid 0:08:35.920 --> 0:08:40.360 salts per minute through the receiver circuits that run back 0:08:40.400 --> 0:08:44.240 and forth across the inside of these black panels. So 0:08:44.559 --> 0:08:47.120 imagine you've got this really tall tower. At the top 0:08:47.160 --> 0:08:50.800 of the tower, you have these fourteen dark panels, and 0:08:50.840 --> 0:08:53.040 then let's just take seven on one side. You've got 0:08:53.040 --> 0:08:54.920 seven of those dark pounds on one side. On the 0:08:55.040 --> 0:08:58.240 inside of those panels, you would see this criss crossing 0:08:58.559 --> 0:09:03.920 of a pipe that is circulating liquid salts through the pipe. 0:09:04.840 --> 0:09:08.440 Heat from the outside comes into the tower and it 0:09:08.440 --> 0:09:12.000 begins to heat those liquid salts running through that circuit. 0:09:12.640 --> 0:09:15.600 It's a simple heat transfer. And if you've listened to 0:09:15.640 --> 0:09:19.280 our podcasts about things like refrigerators and air conditioners, you 0:09:19.360 --> 0:09:21.920 know about you know how this, what the principles are, 0:09:22.120 --> 0:09:25.200 how how this is based same basic thing. You want 0:09:25.200 --> 0:09:27.800 to give as much surface area you know you want 0:09:27.800 --> 0:09:29.400 to you want to dedicate as much surface area as 0:09:29.400 --> 0:09:31.480 you can to heat and have the liquid salts cross 0:09:31.559 --> 0:09:33.720 over as much of that surface area as as possible 0:09:33.760 --> 0:09:38.319 to heat up the liquid salts. As the liquid salts 0:09:38.400 --> 0:09:43.360 move through the circuit, they become molten, so incredibly high temperatures. 0:09:44.200 --> 0:09:48.040 So the low side of the temperatures for these liquid 0:09:48.040 --> 0:09:50.679 salts is five hundred and fifty degrees fahrenheit or two 0:09:50.800 --> 0:09:54.520 hundred eighty eight degrees celsius. That's the low end. That's 0:09:54.600 --> 0:09:57.280 that's the chili side. If you want to talk about 0:09:57.280 --> 0:09:59.240 how hot they get, they can get up to a 0:09:59.320 --> 0:10:03.320 thousand ifty degrees fahrenheit or five hundred and sixty six 0:10:03.400 --> 0:10:08.120 degrees celsius. That's really impressive. And so you've got this 0:10:08.320 --> 0:10:12.280 massive amount of stored thermal energy. It's all inside the 0:10:12.320 --> 0:10:15.480 molten salts. So you've got a lot of heat stored up. 0:10:16.120 --> 0:10:19.320 What good is heat, Well, you can use heat to 0:10:19.440 --> 0:10:22.360 do the same thing that is done in power plants 0:10:22.480 --> 0:10:26.439 all over the world. You use heat to turn water 0:10:26.480 --> 0:10:30.160 into steam and use the steam to turn a turbine, 0:10:30.400 --> 0:10:35.200 which generates electricity. It's an incredibly simple idea. It's the 0:10:35.240 --> 0:10:39.680 basis of almost every other type of power plant, with 0:10:39.800 --> 0:10:43.680 the exception of things like solar panels that are used 0:10:43.679 --> 0:10:47.960 in solar farms. Like that's generating electricity straight from sunlight, 0:10:48.000 --> 0:10:52.000 as opposed to using that electricity to somehow turn water 0:10:52.080 --> 0:10:54.000 into steam. That would be ridiculous. You would lose way 0:10:54.040 --> 0:10:56.480 too much energy in that approach. But things like coal 0:10:56.559 --> 0:11:00.680 fired plants, even nuclear power plants, you're talking about generating 0:11:00.720 --> 0:11:04.960 electricity by heating up water into steam and using that 0:11:05.000 --> 0:11:07.480 steam to turn a turbine to do work, and that 0:11:07.600 --> 0:11:10.559 turbine ends up being an electric generator and you get 0:11:10.559 --> 0:11:16.240 electricity from that. So the purpose of the solar tower 0:11:16.400 --> 0:11:19.600 is really just to collect heat that's it. It's not 0:11:19.679 --> 0:11:23.319 doing anything magical. It's just generating tons and tons of heat. 0:11:23.720 --> 0:11:26.600 I know that tons is not really a unit when 0:11:26.640 --> 0:11:28.800 it comes to heat or temperature, but you understand what 0:11:28.840 --> 0:11:31.800 I mean. It creates an enormous amount of heat, and 0:11:31.880 --> 0:11:34.679 the molten salts then go into a big storage tank. 0:11:35.400 --> 0:11:38.800 And it's pretty cool because that storage tank ends up 0:11:38.880 --> 0:11:42.240 being a way of holding onto the heat for a 0:11:42.280 --> 0:11:46.520 long time. According to Solar Reserve, the company says that 0:11:46.559 --> 0:11:49.800 the molten salt only loses one degree of fahrenheit or 0:11:49.840 --> 0:11:54.240 about point five, five, five, etc. Etc. Degrees celsius in 0:11:54.400 --> 0:11:58.440 heat per day. So, in other words, if you have 0:11:58.679 --> 0:12:01.840 a long stretch of over days, you still have this 0:12:02.040 --> 0:12:06.200 massive vat. Really tank, it's not a vat, it's a 0:12:06.240 --> 0:12:10.240 tank because it's completely enclosed of molten salts and they 0:12:10.280 --> 0:12:13.120 hold onto that heat, which means you can continuously pump 0:12:13.200 --> 0:12:17.320 that through your water tank in order to heat water 0:12:17.440 --> 0:12:19.840 up to steam. And when I say pump it through, 0:12:20.000 --> 0:12:23.000 it's a very similar circuit that you would find at 0:12:23.040 --> 0:12:27.800 the top of the receiver. The molten salts don't mix 0:12:27.880 --> 0:12:30.920 with the water. Instead, you have a pipe that runs 0:12:30.960 --> 0:12:34.440 through the water tank. The molten salts run through the 0:12:34.440 --> 0:12:37.480 pipe and transfer some of their heat to the water 0:12:38.040 --> 0:12:41.920 through the material of the pipe itself. So you're not 0:12:42.000 --> 0:12:44.560 laying the molten salts in the water mixed together. That 0:12:44.600 --> 0:12:48.120 would be ridiculous. Instead, you're having the molten salts move 0:12:48.200 --> 0:12:50.920 through a pathway, and as they move through that pathway, 0:12:50.960 --> 0:12:53.520 they heat up the water. The water turns, the steam 0:12:53.559 --> 0:12:56.840 turns the turbine. Then the steam goes through a condenser 0:12:57.360 --> 0:13:00.480 to condense the steam back into water and goes back 0:13:00.480 --> 0:13:03.839 into the water tank. So once you use the molten 0:13:03.880 --> 0:13:07.200 salts to transfer some of this heat, they've lost that 0:13:07.360 --> 0:13:11.920 thermal energy. They're now moving into a different tank. It's 0:13:11.920 --> 0:13:14.800 a tank to pump the liquid salts back up into 0:13:14.840 --> 0:13:18.600 the top of the tower. So the neat thing with 0:13:18.679 --> 0:13:22.440 this system is that you can use it to deliver 0:13:22.480 --> 0:13:25.480 electricity day or night. You've got so much stored heat. 0:13:25.559 --> 0:13:27.920 After you get the system up and running and it's 0:13:27.960 --> 0:13:30.760 generated enough molten salt, like it's created enough molten salt 0:13:30.800 --> 0:13:34.440 through this process to allow this to happen, you can 0:13:34.640 --> 0:13:37.920 deliver electricity on demand twenty four hours a day, and 0:13:37.960 --> 0:13:41.400 that's how all power plants work. They deliver electricity on demand. 0:13:41.400 --> 0:13:44.800 They're not set to a certain level, and then if 0:13:44.800 --> 0:13:47.520 you don't meet that level, they you know, just that 0:13:47.559 --> 0:13:51.200 electricity goes to waste. They base it upon what the 0:13:51.360 --> 0:13:53.520 current demand. And I don't mean that as a pun, 0:13:53.640 --> 0:13:55.480 but it came out of that way. Chris would be 0:13:55.520 --> 0:14:00.000 so proud. They don't. They respond to whatever the demand 0:14:00.000 --> 0:14:02.400 and is at that time to produce the amount of 0:14:02.400 --> 0:14:07.760 electricity needed. So super interesting way of doing this by 0:14:08.360 --> 0:14:11.640 using the sun as an energy source to create the 0:14:11.760 --> 0:14:14.960 heat needed to turn water into steam and turn a turbine, 0:14:15.400 --> 0:14:18.200 as opposed to a fossil fuel like coal or oil, 0:14:18.640 --> 0:14:21.880 or a nuclear fuel in the case of nuclear fusion. Now, 0:14:21.880 --> 0:14:25.040 if we ever are a fission, I should say nuclear fission. 0:14:25.440 --> 0:14:27.000 I know all of you were ready to write in, 0:14:27.200 --> 0:14:29.400 and you should be because that was a silly mistake 0:14:29.440 --> 0:14:32.440 I made nuclear fusion. If we ever crack that nut, 0:14:33.240 --> 0:14:37.240 solar towers may seem quaint in comparison, but that's a 0:14:37.360 --> 0:14:41.040 very difficult problem in physics to solve. So we're still 0:14:41.080 --> 0:14:44.960 waiting on that. We'll conclude our episode on how solar 0:14:45.000 --> 0:14:58.840 towers work after these brief messages. So the neat thing 0:14:58.880 --> 0:15:01.520 about this obviously is that if you do have that 0:15:01.600 --> 0:15:04.360 amount of space, you can really offset a lot of 0:15:04.520 --> 0:15:09.560 a community's electricity needs with a solar tower. And the 0:15:09.600 --> 0:15:13.320 company thinks that the lifespan of these solar towers is 0:15:13.440 --> 0:15:17.520 somewhere in the area of about thirty years, meaning that 0:15:17.680 --> 0:15:19.760 after thirty years you would have to start to replace 0:15:19.840 --> 0:15:23.120 parts because just of wear and tear, or they would 0:15:23.120 --> 0:15:27.560 not be as efficient as they had previously been. So, 0:15:27.840 --> 0:15:31.440 for example, those panels, if the panels become less efficient 0:15:31.480 --> 0:15:34.920 at transferring heat over time, you would definitely want to 0:15:34.960 --> 0:15:37.800 replace them because you would be transferring less heat to 0:15:37.880 --> 0:15:41.040 generate your molten salts will be at a lower temperature. 0:15:41.040 --> 0:15:44.840 It would require more of them to turn water into steam, 0:15:45.600 --> 0:15:48.320 who become less efficient overall. So you have to make 0:15:48.360 --> 0:15:53.440 sure that all the parts are working. They're very few 0:15:53.520 --> 0:15:55.920 moving parts, which is awesome, but you have to make 0:15:55.960 --> 0:15:59.480 sure they're working throughout the lifetime of the facility and 0:15:59.520 --> 0:16:03.000 then obviously replace parts as needed. So the question then 0:16:03.040 --> 0:16:07.920 becomes doesn't make financial sense to switch over to using 0:16:07.920 --> 0:16:12.000 solar towers at least to offset electricity generation in a 0:16:12.040 --> 0:16:15.240 particular area. To answer that question, you have to look 0:16:15.280 --> 0:16:18.040 at a lot of different factors, and it is way 0:16:18.120 --> 0:16:21.160 more complicated than just a simple yes or no. For 0:16:21.240 --> 0:16:26.440 one thing, how much solar exposure is the area getting. Obviously, 0:16:26.480 --> 0:16:28.360 if you're not getting a lot, then that's not going 0:16:28.400 --> 0:16:31.360 to be a good choice for solar towers or a 0:16:31.400 --> 0:16:33.480 good place to put a solar tower. I should say 0:16:34.560 --> 0:16:38.800 also not just where, and you know what time of 0:16:38.880 --> 0:16:41.320 year do you get solar exposure? Those would be two 0:16:41.320 --> 0:16:45.320 big things. But how much does electricity cost in that 0:16:45.360 --> 0:16:47.760 region already? And the reason why you have to ask 0:16:47.840 --> 0:16:51.000 that question is if you were to provide electricity through 0:16:51.320 --> 0:16:55.880 the solar reserve system, would it make financial sense to 0:16:55.920 --> 0:16:59.680 make that switch? If coal is incredibly cheap in the area, 0:17:00.000 --> 0:17:03.360 and financially it might make more sense to stick with coal, 0:17:03.480 --> 0:17:07.199 even though we all know there are big environmental drawbacks 0:17:07.240 --> 0:17:09.480 to using coal. You create a lot of fossil fuels, 0:17:09.480 --> 0:17:13.359 you have a big carbon footprint that way, But it's 0:17:13.400 --> 0:17:19.040 hard to argue with the dollar cost of energy. If 0:17:19.080 --> 0:17:23.800 that dollar cost is higher with solar reserve, that's a 0:17:23.800 --> 0:17:27.320 tough sell because not everyone's willing to spend more money 0:17:27.680 --> 0:17:34.000 to keep their homes supplied with electricity just so that 0:17:34.040 --> 0:17:37.879 they have a lower carbon footprint with the electricity generation. 0:17:38.680 --> 0:17:40.760 It's just the truth of the matter, and some people 0:17:40.800 --> 0:17:44.879 don't have the money to afford the luxury. Obviously, now, 0:17:44.920 --> 0:17:48.440 if solar reserve is able to be significantly less expensive 0:17:48.480 --> 0:17:52.119 than whatever the alternatives are, that's a huge win for 0:17:52.240 --> 0:17:56.000 solar towers. So it's a lot of different questions along 0:17:56.000 --> 0:17:59.920 those lines. Obviously, there are other questions to ask why 0:18:00.119 --> 0:18:02.960 is the carbon footprint of actually building the solar tower? 0:18:03.520 --> 0:18:06.560 But I would argue that whatever it is, it probably 0:18:06.760 --> 0:18:11.959 is significantly less than the carbon footprint produced over the 0:18:12.000 --> 0:18:15.199 lifetime of a coal plant or a gas plant or 0:18:15.200 --> 0:18:21.199 oil plant. I think that's a pretty fair assumption, but 0:18:21.240 --> 0:18:25.000 it still could be a very large upfront carbon footprint 0:18:25.280 --> 0:18:28.760 creation there. So that's kind of the approach that I 0:18:28.840 --> 0:18:30.800 wanted to talk about, this idea of being able to 0:18:30.800 --> 0:18:33.959 generate electricity twenty four hours a day using sun power 0:18:34.119 --> 0:18:37.840 without it being a solar panel, and I thought it 0:18:37.880 --> 0:18:42.360 was a really cool approach to that, something that could 0:18:42.400 --> 0:18:47.600 really get around a tricky problem with solar power, because 0:18:47.720 --> 0:18:50.320 I know a lot of critics point out, hey, if 0:18:50.320 --> 0:18:53.760 the sun's not shining, then you're not making electricity. Well, 0:18:54.400 --> 0:18:57.119 that's true with your traditional solar panels, but not with 0:18:57.200 --> 0:19:02.720 solar towers, assuming that you don't enter into cataclysmic event 0:19:02.800 --> 0:19:06.600 where you've got crazy overcast skies for a really long time, 0:19:06.720 --> 0:19:08.399 in which case, if we do have that, we're going 0:19:08.440 --> 0:19:10.919 to have other problems besides where we get our electricity. 0:19:11.920 --> 0:19:13.840 Oh and you might want to know how much electricity 0:19:13.880 --> 0:19:16.440 can one of these facilities generate. It would be good 0:19:16.440 --> 0:19:19.040 for me to tell you that. So Solar Reserve says 0:19:19.119 --> 0:19:22.240 that depending on the plant design, it can generate between 0:19:22.240 --> 0:19:26.160 fifty and two hundred megawatts over electricity, and one megawatt 0:19:26.240 --> 0:19:30.040 is enough power to supply around a thousand homes. So 0:19:30.160 --> 0:19:33.879 you're talking about with one solar tower facility between fifty 0:19:33.880 --> 0:19:37.399 thousand and two hundred thousand homes. Obviously, there are a 0:19:37.440 --> 0:19:39.399 lot of cities that are bigger than that, and in 0:19:39.520 --> 0:19:42.480 order to supply the electricity for those cities, you would 0:19:42.560 --> 0:19:47.960 need multiple solar tower facilities to do that. And again 0:19:48.080 --> 0:19:51.480 that's another question is where would this be most appropriate. 0:19:51.560 --> 0:19:55.000 Obviously a lot of desert towns that have medium to 0:19:55.160 --> 0:19:59.600 small populations, this would be an amazing approach to generating 0:19:59.600 --> 0:20:03.760 electric but it might not work for someplace like New 0:20:03.840 --> 0:20:08.280 York city for multiple reasons, the population size, the lack 0:20:08.400 --> 0:20:12.119 of land to dedicate to solar power. Obviously, that's another issue, 0:20:12.240 --> 0:20:15.200 is that if you are going to dedicate a land 0:20:15.240 --> 0:20:17.800 to a solar tower facility, you're not able to use 0:20:17.840 --> 0:20:21.639 that land for other stuff, at least not easily, So 0:20:22.000 --> 0:20:25.080 that's another consideration. Obviously, you don't want to end up 0:20:25.119 --> 0:20:27.640 going to a place where you're dedicating land that could 0:20:27.680 --> 0:20:32.760 be otherwise used for a more productive purpose, possibly not 0:20:33.000 --> 0:20:35.760 energy related. It might be food related, or water or 0:20:35.800 --> 0:20:38.399 something along those lines. So a lot of things to 0:20:38.400 --> 0:20:41.120 take into consideration, but I think it's a very elegant 0:20:41.119 --> 0:20:45.159 approach to generating electricity in using a renewable resource the 0:20:45.240 --> 0:20:50.399 Sun's energy, and very low impact to the environment. The 0:20:50.440 --> 0:20:55.000 mountain salts are inert, they're not dangerous. They're obviously dangerous 0:20:55.000 --> 0:20:56.920 in their temperature. You would not want to touch them 0:20:56.920 --> 0:21:00.480 while they're at one thousand and fifty degrees fahrenheit, but 0:21:01.440 --> 0:21:05.280 they're not dangerous to the environment. And these, again the 0:21:06.000 --> 0:21:08.879 systems are separate. The water system and the salt system 0:21:08.920 --> 0:21:11.719 are separate from each other. So I think it's a 0:21:11.760 --> 0:21:14.760 really interesting approach. Now I'm curious to hear what you 0:21:14.760 --> 0:21:19.800 guys think about the most promising energy sources for the future. 0:21:19.920 --> 0:21:22.359 Do you really think that solar power is going to 0:21:22.400 --> 0:21:27.200 become a major way to offset our electricity generation. I'm 0:21:27.240 --> 0:21:30.879 pretty sure. I feel fairly confident it's never going to 0:21:30.920 --> 0:21:35.320 be the primary way we generate electricity. I don't think 0:21:35.320 --> 0:21:39.200 it's practical enough to be our primary, but I certainly 0:21:39.200 --> 0:21:44.520 see it as a very strong contender for a support system, 0:21:44.760 --> 0:21:48.560 something that can offset some of our electricity needs. But 0:21:48.640 --> 0:21:49.920 what do you think? Do you think there are other 0:21:49.960 --> 0:21:53.119 ones that are better? Do you think wind power is 0:21:53.200 --> 0:21:58.320 better than solar? Or maybe maybe you think hydropower is better, 0:21:59.000 --> 0:22:03.480 Maybe think geothermal. Maybe you're looking for that nuclear fusion 0:22:03.800 --> 0:22:06.920 approach if that break If there is a breakthrough nuclear fusion, 0:22:06.920 --> 0:22:09.520 that would be an enormous benefit to all of humanity 0:22:10.359 --> 0:22:14.320 because we would suddenly be capable of going into an 0:22:14.359 --> 0:22:18.959 era of energy surplus, which would be phenomenal. And I 0:22:19.000 --> 0:22:22.879 hope it happens. Hope you enjoyed that classic episode of 0:22:22.920 --> 0:22:26.119 tech Stuff how solar towers work. I might need to 0:22:26.119 --> 0:22:29.960 do an update on the various ways that we can 0:22:30.040 --> 0:22:34.280 use solar power to generate electricity. If you have suggestions 0:22:34.320 --> 0:22:36.680 for topics I should cover in future episodes of tech Stuff. 0:22:36.800 --> 0:22:39.840 Let me know by using the iHeartRadio app, which is 0:22:39.920 --> 0:22:43.040 free to use, free to download. Navigate over to tech Stuff. 0:22:43.040 --> 0:22:45.919 You'll see there's a little microphone icon you click on 0:22:45.960 --> 0:22:47.879 that you can leave me a voice message up to 0:22:47.920 --> 0:22:50.160 thirty seconds in length, or you can let me know 0:22:50.640 --> 0:22:52.320 what you would like me to cover in the future 0:22:52.480 --> 0:22:56.240 by going to Twitter and tweeting me. The show handle 0:22:57.040 --> 0:23:01.080 is tech Stuff HSW and I'll talk to you again 0:23:01.760 --> 0:23:11.399 really soon. Y. Text Stuff is an iHeartRadio production. For 0:23:11.560 --> 0:23:16.400 more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, 0:23:16.520 --> 0:23:18.520 or wherever you listen to your favorite shows.